Exam 1 Review

Question 1

The study of inheritance pattern of petal color in tulips would fall under which branch of genetics?

Answer 1

transmission genetics

Question 2

An early idea about heredity stated that information from different body parts traveled to the germ cells to be passed on was:

Answer 2

pangenesis

Question 3

Model organisms used in genetic research_____.

Answer 3

reproduce quickly and are easily maintained in a lab

Question 4

Watson and Crick used this kind of data collected by Rosalind Franklin to create their double helix model

Answer 4

X-ray crystallography

Question 5

In b-form there are ____ basepairs per turn of the helix.

Answer 5

10

Question 6

The _____ of a DNA helix turns the opposite direction (left handed) than the cellular form of DNA.

Answer 6

z-form

Question 7

Prokaryotes condense their DNA by using:

Answer 7

supercoiling, loops, scaffolding proteins

Question 8

The 3’ to 5’ exonuclease activity of DNA pol III activity allows it to:

Answer 8

proofread and fix mistakes

Question 9

Primers are required for DNA synthesis because:

Answer 9

DNA pol III needs an available 3’-OH to begin synthesis
DNA pol III does not bind single stranded DNA

Question 10

What does chromatin consist of

Answer 10

DNA + protein

Question 11

A gene that is highly expressed would be found where?

Answer 11

euchromatin

Question 12

Eukaryotic DNA replication is different than prokaryotic DNA replication in all ways except:

Answer 12

Eukaryotes have only one kind of DNA polymerase

Question 13

Change in phenotype due to changes in gene expression, but without mutation of DNA sequence is =:

Answer 13

epigenetics

Question 14

What is the entire complement set of DNA molecules in a cell known as?

Answer 14

genome

Question 15

Different forms of the same gene are?

Answer 15

alleles

Question 16

Heritable changes in the DNA sequence are called…

Answer 16

mutations

Question 17

If a molecule is 15% guanine, the percentage of adenosine would be __

Answer 17

35%

Question 18

Heterochromatin is most often found at the _____ and ______ of a linear chromosome.

Answer 18

centromere and telomere

Question 19

DNA that is negatively supercoiled has _____ base pairs per turn.

Answer 19

fewer

Question 20

The central dogma outlines the flow of information:

Answer 20

DNA, RNA, Protein, Function

Question 21

T or F: DNA molecules have both 2’ and 3’ -OH groups

Answer 21

false

Question 22

T or F: DNA is always synthesized in a 5’ to 3’ direction

Answer 22

true

Question 23

Why is DNA always synthesized in a 5’ to 3’ direction?

Answer 23

It is synthesized in a 5’ to 3’ direction because the 3’ has a hydroxyl group attached to it which is necessary for the phosphate group of the next nucleotide to bind to.

Question 24

Describe the experiment conducted and the conclusions made by Griffith.

Answer 24

the experiment conducted by Griffith took place in 1928. The goal of this experiment was to determine what store genetic information. In this experiment, Griffith has 4 flasks with different mixtures that he injected into the mice. The first flask contained virulent bacteria which killed the mouse. The second contained nonvirulent bacteria which didn’t kill the mouse. The third contained a heat killed virulent bacteria which didn’t kill the mouse. However, in the fourth flask he mixed nonvirulent bacteria and heat killed bacteria and it killed the mouse. His conclusion was that something genetically transformed the heat killed virulent bacteria.

Question 25

List 5 features of the Watson and Crick double helix model of DNA.

Answer 25

• 1953
• Double helix
• right handed turn
• sugar phosphate backbone
• 10 bp per turn
• antiparallel strands

Question 26

List three differences between DNA and RNA.

Answer 26

• DNA is double stranded while RNA is single stranded.
• DNA contains deoxyribose sugar while RNA contains ribose sugar
• DNA contains the base thymine but RNA has uracil

Question 27

What are the events required for DNA replication initiation?

Answer 27

• DnaA bind OriC
• DNA region near to OriC melts, creating a small bubble of ssDNA
• ss binding protein maintains bubble
• helicase binds
• primase is recruited
• leading and lagging strands primed

Question 28

Describe synthesis of the lagging strand during DNA replication in E.coli cells.

Answer 28

• primase adds RNA primer to lagging strand and provides an 3’ OH- group.
• Beta clamp attaches to the primer and recruits DNA pol III
• DNA pol III attaches and begins adding nucleotides to the 3’ OH group of the primer.
• DNA pol III synthesizes DNA until it reaches the previous Okazaki fragment.
• pol I comes and replaces the RNA primer with DNA nucleotides
• ligase seals the gaps between the nucleotides with phosphodiester bonds

Question 29

List the steps of the “Trombone Model” model of the lagging strand DNA synthesis.

Answer 29

1. beta clamp binds to primer on lagging strand
2. DNA pol III attaches to the beta clamp
3. DNA pol II synthesizes in a 5’ to 3’ direction until it reaches previous Okazaki fragment.
4. DNA pol III releases lagging strand but is tethered by the clamp loader.
5. DNA pol III binds to new primer

Question 30

Describe the structure of a eukaryotic nucleosome. Provide one reason nucleosomes are important.

Answer 30

• composed of a histone octomer and supercoiled DNA that is wrapped around 2 times.
• the histone octomer 146 bp is made up of 8 proteins including, H2A, H2B, H3 and H4 and . These proteins form two disks and the supercoiled DNA wraps around the histone twice
• nucleosomes are important because they condense and package the DNA and hold it together in nucleosomes so that it is compacted and won’t unravel.